set CALIBRE_DEVELOP_FROM="C:\Documents and Settings\shop1\calibre\src"
calibre-debug -g

Assuming I have the paths right (they are copied from a previous message), calibre should run from source. You should see an asterisk next to the version number. You will be using your standard configuration.

If this doesn't work, then either the path does not lead to the right place or there is something wrong with the source folders. The 'right place' will contain the folders routes, calibre, cherrypy, odf, and pyPdf.